In the firing of industrial oil burners and auxiliary or igniter burners associated with large utility burners, it has been a conventional practice to employ steam as an atomizing agent for the fuel oil. Further, the same source of steam is conventionally employed in the purging of fuel oil lines for safety and other considerations. Three (3) valves are ordinarily employed in order to accommodate the various valving functions, e.g. closing both steam and fuel oil lines, introducing steam to the fuel oil line in the purge operation, and passing steam and fuel oil respectively through the steam and fuel oil lines for a running operation.